Preheat the oven to 350°F (177°C). Grease a 9×13'' baking dish with butter or baking spray and line the pan with parchment paper, leaving an overhang.

Add the butter and bittersweet chocolate to a large, microwave-safe mixing bowl. Melt the butter and chocolate together in 30-second increments, stirring with a rubber spatula in-between, until it's smooth and fully melted.

Add the sifted cocoa powder. Using a hand mixer, beat the mixture until it's very smooth. Then, add the sugar and brown sugar. Beat until the sugar is very well combined and starting to dissolve, about 2-3 minutes.

Stir in the neutral oil, espresso powder (if using), and vanilla extract. Then, add the eggs one at a time. Turn the mixer to high and beat the chocolate mixture until it's lightened in color and texture, about 3-4 minutes.

Fold the flour and salt into the chocolate mixture, stirring just until there are no more streaks of flour. Spread the batter evenly in the prepared 9×13 pan.

Bake the brownies for 16-20 minutes, until the edges are set and the center is still a bit underdone. To test if the brownies are done, insert a toothpick into the area in-between the edges and center of the brownies. If the toothpick has just a few moist crumbs, they're ready to go.

Let the brownies cool completely at room temperature. Then, cover and refrigerate the brownies for 1-2 hours (optional but highly recommended for extra easy slicing). Using the edges of the parchment paper, remove the brownies from the pan.

Grease the mini football cookie cutter and use it to cut out as many brownies as you can. Wipe the cutter in-between slices to prevent the edges from getting crumby, which can cause the brownies to fall apart. You should get about 40 brownies total.

Add the unsalted butter and half of the powdered sugar to a medium mixing bowl. Using a hand mixer, beat the butter and powdered sugar until it's fluffy. Add the remaining powdered sugar and beat until the frosting is smooth.

Add the milk, vanilla, and a pinch of salt. Turn the mixer to high and whip the frosting until it's super light and fluffy, 3-4 minutes. If the frosting is too thick, add more milk 1 teaspoon at a time.

Fit a piping bag with a small round piping tip. I used Wilton tip #2. Fill the piping bag with the vanilla buttercream.

Working one brownie at a time, pipe a long horizontal line across the football. Then, flip the brownie 90° and pipe 3 vertical lines across the horizontal line to create the laces. Repeat this process with the remaining brownies and enjoy!